Controlling device for electric motors.



C. D. KNIGHT. LING DEVICE FOR ELECTRIC MOTORS. APPLICATION FILED FEB.21, 1907.

CONTROL 2 SHEETS-SHEET 1.

Patented Aug. 10,

Fig].

way,

G. D. KNIGHT. GONTROLLING DEVICE FOR ELECTRIC MOTORS,

APPLICATION FILED PEB.21,19Q7.

Patented Aug. 10, 1909.

M'inesses:

UNITED srnrns rnrnur onnrcn.

CHARLES D. KNIGHT. 01-" SCUENJZCTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A (IORIORATIOX OF NEW YORK.

CONTROLLING DEVICEFOR ELECTRIC MOTORS.

Specification of Letters Patent.

Patented Aug. 10, 1909.

To 1/11 Whom it may concern:

Be it known that 1, CHARLES l). KNIGHT, a

citizen of the United States, residing at Schenectady, county ofSchenectady, State of New York, have invented certain new and usefulImprovements in Controlling Devices for Electric Motors, of which thefollowing is a specification.

This invention relates to means for controlling electric motor circuitsand has for its object the provision of a device whereby an electricmotor may be started and brought up to running speed in areliable, safeand efficient manner.

Myinventionrelates more specifically to the starting of alternatingcurrent motors of the induction type.

[n the starting of induction motors of the slipring type it is essentialthat the secondary circuit be closed through the necessary resistancebefore'the closing of the primary circuit. it is also desirable thatmeans he -provided for cutting the resistance out of the "secondarycircuitin a convenient manner. In carrying outmy invention therefore 1provide in connection with automatic means for cuttingthe resistance outof the secondary circuit, electrical connections whereby the primarycircuit cannot be closed until the secondary circuit is closed throughthe entire resistance, and whereby the automatic mechanism begins to cutresistance out of the secondary-circuit as soon as'the primary circuitis closed.

ln the accompanying drawings, in which I have shown my inventionembodied in two different forms, Figure 1. is a view of my'devicecontrolling a three-phase induction motor, and Fig; 2 is a similar Viewof a modified i'orm of iny invention, in which contactors are used forautomatically cutting out the resistance from the secondary circuit,controlling the same type of motor.

Referring to Big. 1 of the drawings, P is the primary and S is thesecondary of an induction motor of the slip ring type, and 1, 2 and 3aret-he three-phase mains from which the motor is operated. The primarycircuit is closed'by means OfSOlGllOld switches 4 4: having cores 5 5,respectively, theformer for o crating the motor in one direction ofrota' tion and the latter for reversing it. Connect- -.edi n series withthe windings of the secondcry a e ee e ces 7 an 8 cont ed the threeresistances.

,9 is operated by a solenoiddO acting upon a core 11 connected to theelement Qby a rod 12. To the lower end oi'the rod is connected adash-pot 13, the barrel of which is pivoted to the under side of arm 9while the piston 14 is pivoted at 15. 'The arm 9 is normally down in theposition shown, having a bias to this osition by virtue of its weight orby any 0t or desired agency. The'dashpot is designed to permit the arm 9to move upward freely but operates to retard it upon its return. When te arm 9 is down the resistances 6, 7 and 8 are short-circuited while, 5when it is in the upper position, the resistances are all in circuit.

The two solenoid switches 4 and 4, which control the primary circuit,are identical in construction and operation and consist simply of solenods, each having a core carry ng three'bridging contacts 16, 17 and 18,and 16, 17 and 18, respectively. When the solenoids are energized, thesecontacts are raised and bridge the corresponding contacts to close thethree phases of the primary circuit. Bridging contacts 18 andlS', whenin their lower position, complete the circuit of the solenoid 10, andwhen moved up, break the same. The contacts are held in the raisedposition by means of latches l9 pivoted at 20 arranged to engageextensions 21 of the cores 5 5 of the solenoids to latch the same in araised position. The latches are; held in by means of solenoids 22 whichare connected in ,circuit so as to be'energized upon the closing of themain switch and act a ainst thetension of their springs 21 to hol thelatches in an operative position. The circuits of solen oids land 4 arecompleted through contacts 23 and23', which are bridged b means ofcontacts 24 and 24 on the arm, w en the latter isin its raised osition.A switch 25 is arran ed to close the circuit through either one o thesolenoids l 0r 4', depending upon the direction of rotation desired.

The arrangement of circuits and mode of operation is as follows: Whenthe switch 25 is closed on the contact stud 26, current will ba k tolineat main At the same the solenoid 22 is energized between the mains 1 and3 from conductor 27 to conductor 32. The solenoid being energized, thecontrolling arm 9 is raised until it reaches the upper position wherethe circuits of the solenoids 4 and 4 are closed by the contacts 24 and24 bridging contacts 23 and 23. In this position all of the resistances6, 7 and 8' are in the secondary circuit. As soon as the cont-acts 23are bridged, the solenoid 4 is energized, current passing therethroughas follows: from conductor 27 through solenoid 4, conductor 33, contacts23 and conductor 31, back to line at main 2. The solenoid beingenergized, it closes the three phases of the primary circuit at contacts16, 17 and 18. The lattercontact as it rises opens the circuit of thesolenoid 1O whereupon the core 11 is released. The arm 9 thereupon dropsand is retarded by the dash-pot 13. As the arm drops, the motor speedsup and when the lowest position is reached the motor is running at fullspeed. If the switch arm is moved on to the stud 34, the direction ofro- .tation of the motor will be reversed but the operation will be thesame. .Current will then pass from switch through conductor- 35, bridge18, conductor, 36, solenoid 10, thence back to line as before throughconductor 28. 'The solenoid 4 is energized from conductor to conductor37, contacts 23 and conductor 31, back to line at main 2. In order tostop the motor quickly as is sometimes desired, especially where themotor is used to operate a hoist or an elevator,-I provide a brake 38controlled by solenoid 39. As soon as the primary circuit is closed, thesolenoid 39 is energized and the brake withdrawn from the mot-or. Uponfailure of voltage, solenoids 22 are decnergized to openthe primarycircuit.

In Fig. 2 I have shown a similar arrange ment, the only difference beingthat instead of using a single controlling element operating to vary thesecondary resistance, I provide aseries of contactors, each one of whichas it operates cuts out a section of resistance.

When the switch 25 is closed the solenoid 4 is immediately energized.from main 3 ductor 42. This operates as before to close the three phasesof the primary circuit, all of the resistances 6, 7 and 8 being in themeantime in the secondary circuit. In this case the circuit of thesolenoid 4 is opened by the opening of switch 41 after the primary cir*cuits are closed. When the lower contact 18 closesjits circuit thesolenoid 43 of the first contactor is energized as follows: from main 1through conductor 44, bridging contact 18, conductor '45, solenoid 43,conductor 46, bridging contact 47 and back to line at main .3 throughconductor 48. This solenoid "pulls up one eontactor to cut out onesection tact 47.

of resistance, and at the same time closes a circuit through bridgingcontact 49 of solenoid 50. This solenoid in turn operat'es its contactorto cut out another section of resistance, and at the same time by meansof its bridging contact 51 closes the circuit of the next succeedingsolenoid and so on. When the last solenoid 52 is reached, the resistanceis short-circuited and the circuits of all of the other solenoids areopened at con- The contactor of solenoid 52 is held in a raised positionby latch mechanism 53, such as is described in connection with Fig. flThe arrangement shown in Fig. 2 may be used where the currents are hearand the operation will be substantially the same as that described withreference to Fig. 1. H I have shown my invention in connection with aparticular form of motor, i. e., a threephase induction motor of theslip-ring type, but it should be understood that my invention is notlimited to this particular applica tion except in so far as it islimited to the claims annexed hereto.

. hat I claim as new and desire to secure by Letters Patent of'theUnited States, is,- 1. The combination with an alternating currentmotor, of means for controllingthe same comprising an electromagneticswitch for varying the resistance in the secondary circuit and anelectromagnetic switch arranged to be automatically energized to closethe primary circuit when the resistance varying switch is moved to apredetermined position.

2. The combination with. an; alternating resistance is included.

The combination with an alternatingcurrent motor, of means forcontrolling the same comprising an electrically controllerl switch forclosing the primary circuit, an impedance for the secondary circuit, andarary- 1ng mechanism thcrcl'or arranged to control the circuit oi saidswitch.

4. The combination with an alternating current motor, of means forcontrolling the same in opposite directions of rotation comprisingelectromagnetic primary circuit closlng switches one for each direction,an impedance for the secondary circuit, and elec tromagnetic meansarranged to control the circuit of said switches for including saidpedance in the secondary circuit.

5. The combination with an alternating current motor, of means forcontrolling the same comprising an electromagnetic switch for closingthe primary circuit, an impedance for the secondary circuit, and aiautomatswitch for the p current motor,

ically operated varying mechanism therefor arranged to control thecircuit of the primary circuit-closer. I

6: The combination with an same comprising an electrically controlledfor the secondarycircuit, electromagnetic varying mechanism thereforcontrolled by said switch, and connections whereby saidvaryingimechanism controls the circuit of the switch;

7. The combination with current motor, of means for same in oppositedirections electromagnetic switch for an alternating controlling thecomprising. an varying the resistance in the secondary circuit andelectromagnetic switches, one for each direction of rotation, arrangedto be automatically energized to close the primary circuit when theresistance varying switch is moved to a predetermined position. i

8. The combination with an alternating sista'nce normally excluded fromthe secondary circuit, electromagnetic switches one for each directionof rotation for including the resistance in said circuit and anelectromagneticswitch arranged to be automatically energized to closethe circuit when said resistance is excluded.

9. The combination with an. alternating current motor, of means forcontrolling the same comprising automatic means for closing the primarycircuit, a variable impedance for the secondary circuit, a controllingelement therefor having a bias toward the low-impedance position, anelectromagnetic device for moving said element to a high-impedanceposition, and means controlled by the rimary circuit-closer fordeenergizing the e cotromagnetic device to release-the controllingelement.

10. The combination with an alternating current motor, of means forcontrolling the same comprising an electromagnetic switch for theprimary circuit, a variable impedance for the secondary circuit, acontrolling element therefor having a bias toward the low impedanceposition, vice for moving said element to a high-impedance position, andconnections whereby the circuit of the primary circuit is closed whensaid element reaches a predetermined position.

alternating current motor, of means for controlling the rimary circuit,an impedance of means for controlling thesame in opposite directionscomprising a rean electromagnetic decurrent motor, of means for 11 Thecombinationwith an alternating current motor, of means for controllingthe same comprising an electromagnetic switch for the primary circuit, avariable impe-' dance for the secondary circuit, a controlling elementtherefor having a bias toward the low-impedance position, anelectromagnetic device the circuit of which is controlled by said switchfor moving said element .to ,a high-impedance position, and connectionswhereby the circuit of the primary switch is closed when said elementreaches a predeter primary switch is, closed when said elementreachesthe latter position.

13. The combination with an alternating current motor, of means forcontrolling the same in o posite directions of rotation comprising eectrically-controlled switches for the primary circuit one for eachdirection, an

impedance'for the secondary circuit, electromagnetic varying meanstherefor controlled by either of said switches, and connections wherebysaid varyingmechanism controls the circuits of the switches.

14. The combinationwith an alternating controlling the same 1n oppositedirections of rotation comprising electromagnetic switches one for eachdirection, a variable impedance for the secondary circuit, a controllingclement therefor having a bias toward a minimum impedance position, anelectromagnetic device the circuit of which is controlled by eitherofsaid switches for moving said element to a maximum impedance position,and connections whereby the circuits of the primary-switches are closedwhen said element reaches'the latter position.

In witness whereof, l have hereunto set my hand this 19th day ofFebruary, 1907 CHARLES D1 KNIGHT.- Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

